Refrigerated display case



V. W. SMITH REFRIGERATED DISPLAY CASE Filed June 11, 1953 INVENTOR. V/CTOR W. S/W/T/v Nov. 13, 1956 REFRIGERATED DISPLAY CASE Victor W. Smith, Trenton, N. J., assignor to C. V. Hill &

Company, Inc., Trenton, N. J., a corporation of New Jersey This invention relates to self-service refrigerated display cases of the type in which a blower is employed for circulating air through a display space that is open at the top for access to customers. The invention is directed particularly to means for controlling operation of the blower.

The construction of refrigerated display cases and the temperatures maintained in their display spaces vary considerably depending upon the type of product being displayed and refrigerated. Thus, frozen foods are generally kept at temperatures which may vary during the on and off cycles from about l F. to F. Meats are usually kept at temperatures of from about F. to F., whereas vegetables and fruits are kept at temperatures of from about 32 F. to F.

Whatever the temperature maintained in the display space, the motor and compressor by which the refrigerant is circulated is operated in successive on and off cycles, whereas the blower used to circulate the refrigerated air is operated continuously to maintain more uniform temperature conditions throughout the display space. The control of humidity in such cases is always a problem and under some conditions, continued operation of the blower accentuates these difliculties. Moreover, all such equipment is subject to failure from time to time and in the event the compressor or motor in a frozen food or meat case stalls or fails to renew its operation at the end of an off cycle, the resulting undesired rise in temperature is accelerated by continued operation of the blower. Similarly, with vegetable cases the sticking or freezing of an expansion valve may cause the temperature to fall too low in which case continued circulation of the resulting low temperature air will cause the vegetables to freeze or dry out unduly. In either case, a serious loss in produce may occur before the adverse conditions are discovered or can be corrected.

In accordance with the present invention, these objections and difiiculties encountered with self-service refrigerated display cases are overcome and means are provided for controlling operation of the blower so as to maintain the desired humidity in the display space during normal operation and to discontinue operation of the blower when adverse or undesired conditions of refrigeration occur.

These results are attained by arranging the display space in a specific location with respect to the air circulating passages in the case and by providing means responsive to the temperature of air circulating through said passages or the display space for controlling operation of the blower or air circulating means.

One of the objects of the present invention is to provide self-service refrigerated display cases with means for controlling circulation of air over or about articles on display to maintain the desired humidity and temperature conditions more effectively than has been possible heretofore,

Another object of the invention is to provide a selfservice refrigerated display case having a blower with aired States Patent 0 Patented Nov. 13, 1956 means for controlling operation of the blower in response to the temperature of the air being circulated through the display space.

A specific object 'of the invention is to provide a selfservice refrigerated display case with means for terminating operation of the blower used for circulating air through the display space when undesired temperature conditions are encountered.

These and other objects and features of the present invention will appear from the following description thereof in which reference is made to the figures of the drawing.

In the drawing:

Fig. 1 is a-vertical sectional view through a typical form of self-service frozen food or meat case embodying the present invention;

Fig. 2 is a diagrammatic illustration of a preferred form of control means and circuit of the type which may be employed in the construction of Fig. 1;

Fig. 3 is a vertical sectional view through a self-service refrigerated vegetable stand embodying the present invention; and

Fig. 4 is a diagrammatic illustration of a preferred form of control means and circuit of the type which may be employed in the construction of Fig. 3.

In that form of the invention chosen for purposes of illustration in Fig. 1, the refrigerated display case is of the type shown and described in the patent to MacMaster No. 2,494,481, wherein the display space 2 is open at the top for access to customers. The front wall embodies an insulating multiple glass panel 4 mounted on the lower insulated front Wall portion 6, whereas the base 8 and the rear wall 10 of the case are also formed of insulating material. The lower portion of the display space is provided with a rack or support 12 upon which the articles to be refrigerated and displayed are supported. An air circulating passage extends downward from the inlet 14 near the upper edge of the front wall of the display space and communicates with a chamber 16 beneath the article supporting rack 12. A blower 18 is located in the chamber 16 and directs air upward through the rear air passage 20 to the refrigerating coil 22 located in the upper rear portion of the case. rom the refrigerating coil, the air passes outward through the air outlet 24 so that it will flow across the upper portion of the display case returning to the air inlet 14.

The blower 18 is operated independently of the compressor motor 34 and is normally actuated during at least a part of both the 011" and off cycles of refrigeration. The temperature throughout the display space is thus maintained substantially uniform and the articles on display are kept in a properly cooled or cold condition for preservation. At the same time, the articles are accessible to customers reaching into the top of the case to remove or inspect articles,

Current for operating the blower 13 is supplied through the lines 26, whereas the compressor motor 34 is energized by current supplied through lines 28 and 29. A circuit controlling device 30 is connected in the line 28 and is actuated by means of a temperature responsive device 32. During normal operation when the temperature remains below say +10 F., the device 30 serves to control operation of the compressor motor 34 by initiating the usual on and off cycles of the refrigerating equipment. However, in the event the compressor motor or refrigerating equipment should fail for any reason the warm external air, which normally mingles to some extent with the air being circulated by the blower, would not be refrigerated and the temperature would rise substantially above 10 F. endangering the articles on display. Under such circumstances, the device 30 of the present invention further serves to break the blower circuit by breaking the contact 52 including the line 26 so as to discontinue operation of the blower. Thereafter, the air within the display space and about the articles on display remains substantially stagnant and will establish a well of cold air about the articles so as to protect them from the warm air above the open top of the display space and maintain them under adequate refrigeration for a relatively long period of time.

The construction of the circuit controlling device 30 preferred is that illustrated in Fig. 2 wherein the temperature responsive device 32 embodies a bellows 40 connected to the thermal expansion coil 42 located at a suitable position to respond to the temperature of the air being circulated. The bellows 40 expands and contracts with changes in temperature and serves to move the arm 44 of the circuit controlling device 30 about its pivot 45 to close and open the contact 46 for initiating the on and off cycles of refrigeration. In the event the motor or compressor should stall or should fail to renew operation for any other reason upon engagement of the arm 44 with the contact 46 at the conclusion of an ofi cycle, the bellows 40 will continue to expand moving the upper end of arm 44 further to the left as seen in Fig. 2. A rod 50 formed of insulating material is positioned to be engaged by arm 44 as the bellows 40 expands beyond the on position of engagement of contact 46. Rod 50 when so moved serves to break the normally closed contact 52 in the blower circuit whereby operation of the blower 18 is discontinued. Thereafter, the air within the display space will remain stagnant about the articles on display so as to maintain a blanket of relatively cold air about the articles for a long period of time. The articles are therefore refrigerated sufficiently to prevent spoilage until most emergency conditions can be rectified.

In that form of the invention illustrated in Fig. 3, the refrigerated display case is designed for use in the display and preservation of vegetables and is provided with a display space 60 having an adjustable rack or support 62 in the lower portion thereof for receiving and supporting the vegetables, fruit or other articles on display. An air chamber 64 is located below the supports 62 and communicates with the display space through an air inlet 66 near the lower front portion of the display space. A blower 68 is located within the chamber 64 and serves to draw air from the display space through the inlet 66 to the chamber 64. The air is then directed over the refrigerating coil 70 from which it flows upward through the rear passage 72 to the louvers or air outlet 74 in the upper rear portion of the display space. In this way, air at the desired temperature is circulated over the articles supported on the rack 62 in the display space 60 and above the air chamber 64.

With this construction, the circuit arrangement of Fig. 4 may be used. Blower 68 receives current from the lines 76, whereas the compressor motor 80 receives current from the lines 78 and 79. A circuit controlling device 82 connected in the line 78 is provided with an arm 84 actuated by temperature responsive means such as a bellows 86 provided with a coil 88 located at any suitable point in the display case and preferably the upper end of the rear air passage 72.

During normal operation of the device 82 in the construction illustrated in Fig. 3, the contact arm 84 serves to make and break the contact 90 in the line 78 to establish the usual on and off cycles of operation of the compressor motor 80. However, in the event the expansion valve or other elements of the refrigerating system should stick or fail to terminate the on cycle of refrigeration, the temperature of the air being circulated over the articles on display will fall dangerously low and may cause freezing or drying out of the produce. Under such conditions, the insulating rod 92 positioned adjacent the contact arm 84 is engaged by the arm as the bellows 86 continues to contract. The normally closed contact 94 in line 76 is thus opened to break the blower circuit and terminate operation of the blower. The overcooled air about the refrigerating coil 70 will then be allowed to accumulate in the air chamber 64 beneath the article support 62 instead of being directed over the articles through the louvers of air outlet 74. Since the articles on display are supported near the open top of the display space, the warm air from the exterior of the space will come into contact with the articles and will not be driven off by the circulating air as in the normal operation of the equipment. The articles therefore will be kept at a sufliciently high temperature to avoid freezing, drying out or damage to the goods.

The construction of the present invention is further operable to maintain the desired conditions of humidity in the air being circulated. For this purpose, the contacts 52 or 94 which control the fan circuit may be positioned and arranged so as to discontinue operation of the fan and circulation of the air before the conclusion of an on or ofi cycle of refrigeration. If the blower is stopped before the end of an on cycle the articles on display will not be protected from the warm external air by the circulation of the refrigerated air and thus, in the case of refrigerated vegetable stands, the circulation of air may be discontinued prior to the conclusion of an on cycle of refrigeration when the circulating air is at its lower temperature. The warm, moist air from above the display space then will not be driven off by the circulating refrigerated air and as a result, the relatively humid air from above the display space will come into contact with the vegetables on display and cause moisture to deposit on the cooled vegetables. On the other hand, air at the higher temperatures reached during the off cycle and initial portion of the on cycle will be blown over the ice covered coil to take up moisture therefrom to maintain the desired relatively humid conditions.

The reverse situation is often desired when articles such as candy are being refrigerated or when the articles are protected by cellophane or other wrapping materials. it is then desired to prevent the deposition of moisture on the candy or wrapping material and under such conditions, the contact controlling the blower circuit is caused to operate so as to discontinue operation of the blower prior to the conclusion of an off cycle when the temperature of the air is relatively high and moisture is not being extracted from the air by contact with a low temperature refrigerating coil. The air is, instead, circulated when the coil of the refrigerating equipment is at its lowest temperature and capable of carrying only a limited amount of moisture. The humidity of the air is thus kept low and the wrapped articles are maintained in a dry condition avoiding possible deposition and moisture thereon.

It will be evident from the foregoing description of such typical constructions as those illustrated in Figs. 1 and 3, that the arrangement of the elements may be varied for use as a safety device or as a humidity control or both.

The display space and the air circulating passages employed in display cases used for the preservation of frozen foods and meats requires a construction wherein the articles are supported within the display space at a distance substantially below the top of the display space in order that a well of cold air may be maintained about the articles after operation of the blower is discontinued. On the other hand, when the construction is employed in refrigerated self-service display cases for use with vegetables, the air circulating passages should be arranged to provide a relatively large cold air chamber beneath the display space. The support on which the vegetables are located also should be sufficiently close to the top of the display space to permit the entry of warm room air into and about the articles on display when operation of the blower is discontinued. In either case, the blower is controlled by a circuit including a temperature responsive device which serves to break the blower circuit Whenever undesired or dangerous temperatures are encountered.

When the present invention is employed with other types of refrigerated display cases, the construction and arrangement of the display space and air passages may, of course, be varied considerably. It will also be evident that any suitable or preferred type of temperature responsive circuit controlling device may be employed but the device should be actuated in response to the temperature of the air being circulated rather than to a condition of the refrigerating system such as the pressure or temperature of the circulating refrigerant since failure of any kind in the refrigerating system would result in failure of the blower control. Instead of using an expansion coil and bellows for actuating the circuit controlling device, a bi-metallic strip or other temperature responsive element may be used. Furthermore, the temperature responsive element may be located at any preferred or convenient location within the area through which the refrigerated air is circulated.

It will thus be apparent that numerous changes and modifications will be made in the form, construction and arrangement of the elements of the display case, relay and temperature responsive elements of the present invention. The type of blower employed also may be varied considerably. In view thereof, it should be understood that the particular embodiments of the present invention chosen for purposes of illustration are intended to be illustrative only and are not intended to limit the scope of the invention.

I claim:

1. A refrigerated self-service display case comprising means forming a display space which is open for access to customers, a support for articles to be refrigerated located within the display space, an air chamber beneath said support, air inlet and outlet channels for said air chamber, a blower located Within said case in position to circulate air through said air channels and said air chamber to and from the display space, means in said case for refrigerating the air thus circulated, a compressor for delivering refrigerant to said refrigerating means, electrical circuit means for energizing said blower and said compressor, said circuit means including a contact for establishing on and off cycles of operation of said compressor and a contact for normally maintaining an on cycle of operation of said blower, and a single temperature responsive means located within said case in the path of circulation of air by said blower for operated when the temperature of the air being circulated by said blower presents an undesired condition of refrigeration in said display space.

2. A device of the character set forth in claim 1 in which the contacts are moved successively by the temperature responsive means.

3. A device of the character set forth in claim 1 in which the temperature responsive means successively operates the fan and compressor contacts when the display case temperature exceeds a predetermined maximum.

4. A device of the character set forth in claim 1 in which the temperature responsive means successively operates the compressor and fan contacts when the display case temperature falls below a predetermined minimum.

5. A refrigerated self-service display case comprising means forming a display space which is open at the top for access to customers, a support for articles to be refrigerated located near the bottom of the display space, means forming an air chamber beneath said support, air inlet and outlet channels extending from said air chamber to opposite sides of said display space, a blower located within said case in position to circulate air through said air channels and air chamber to and from the display space, means in said case for refrigerating the air thus circulated, a circuit controlling device having a contact arm, temperature responsive means for moving said arm of said circuit controlling device, an electrical circuit controlling operation of said refrigerating means and including a contact actuated by said arm for establishing on and ofi cycles of refrigeration, and an additional contact actuated by said arm to control operation of said blower when the temperature of the air being circulated presents an undesired condition of refrigeration in said display space.

References Cited in the file of this patent UNITED STATES PATENTS 2,009,817 Rodman July 30, 1935 2,178,807 Ploeger Nov. 7, 1939 2,337,089 Ellsworth et al. Dec. 21, 1943 2,451,385 Groat Oct. 12, 1948 2,494,480 MacMaster Jan. 10, 1950 2,494,481 MacMaster Jan. 10, 1950 2,520,370 Olfutt Aug. 29, 1950 2,586,992 Rapuano -2 Feb. 26, 1952 2,594,066 Pabst Apr. 22, 1952 2,608,831 Steelman Sept. 2, 1952 2,630,684 Strang Mar. 10, 1953 

